Exercising devices of the type disclosed in U.S. Pat. No. 4,291,787 are well known to persons skilled in the art and widely used by physical education instructors and physical therapists to strengthen and rehabilitate muscles.
Since body movement involves an extremely complex arrangement of muscles attached to parts of the body to provide movement when the muscles shorten, the maximum force exerted by a body member through a full range of movement varies throughout the range of movement of the body member. For building and rehabilitating muscles, it is desirable that force exerted at various times or angles throughout the range of movement of the body member be known to facilitate prescription of therapy or exercises which will be most beneficial. Further, it is desirable that certain exercises be performed but not others for developing and rehabilitating muscles. For example, for rehabilitating certain knee injuries, it is desirable to provide exercise for certain muscles but not others and to limit movement to a prescribed range.
A primary object of the present invention is to provide sensors associated with a lever or arm which is actuated by the user, in combination with apparatus for indicating power or work done at various angles of rotation.
A further object of the invention is to provide an improved double acting hydraulic cylinder together with a control valve to permit independent adjustment of resistance to movement of the piston in each direction or to resist movement of the piston selectively in either direction but not in the other direction.
In accordance with the invention, the exercising device comprises a frame having a lever arm pivotally secured thereto and a double acting hydraulic cylinder connected between the frame and the lever arm to resist movement of the lever arm. A valve associated with the cylinder is provided with valve elements having passages of varying dimensions to permit independent adjustment of the restriction to fluid flowing from opposite ends of the cylinder such that the force required to extend the rod from one end of the cylinder may differ from the force required to retract the rod back into the cylinder. Pressure transducers are arranged to provide a signal related to pressure required to move the piston through the cylinder in opposite directions. A potentiometer is positioned to supply an output signal related to the position of the lever arm as it rotates about a pivot point. Signals from the pressure transducers and from the potentiometer are delivered through signal conditioning circuits, an analog to digital converter circuit to a microprocessor. The microprocessor is adapted to be reset at the beginning of a timed cycle and to indicate the number of repetitions, elapsed time, accumulated work and power; and work, power and peak load for any single previous repetition. The microprocessor is further adapted to indicate the work or power during flexion and extension of right and left body members for purposes of comparison of the strength of the body members. The output from the microprocessor is delivered to the input of a conventional home computer for data processing, graphic illustration and storage of data.